In a blood donation or the like, when drawing blood from a subject by using a blood drawing apparatus, a blood drawing needle is punctured in the subject, and the blood of the subject is drawn from the blood drawing needle and introduced to a blood drawing bag. At this moment, by sanitizing a puncture position of the subject with alcohol or the like before puncturing the blood drawing needle in the subject, the drawn blood is prevented from being contaminated by bacteria. However, even after the sanitization is performed, the drawn blood can be contaminated by bacteria that are present on a skin or under the skin. When the drawn blood is contaminated by bacteria by mistake, depending on types of the bacteria, the bacteria may grow even during a period of storing the blood in the blood drawing bag or in a collecting bag. If such blood that is contaminated by the bacteria is transfused into other patient, it may cause an infectious disease, which is likely to lead to a serious situation.
For this reason, in order to prevent the drawn blood from being contaminated by the bacteria, particularly to remove initially-drawn blood at the time of drawing the blood, a blood drawing apparatus has been proposed, in which a first flow path for introducing drawn blood to a blood drawing bag and a second flow path for removing initially-drawn blood are connected to each other with a branching part, and a blocking part is provided between the branching part and the blood drawing bag, which blocks the flow path at the initial stage but opens the flow path by an opening operation (see, for example, Japanese Patent No. 3776227).
This blocking part is partially breakable. The first flow path is blocked by the blocking part before being broken, so that the initially-drawn blood is prevented from flowing into the blood drawing bag. On the other hand, when the blocking part is partially broken, the first flow path is opened, so that the drawn blood can be introduced to the blood drawing bag.
Another technology uses a multiway valve as a flow-path switching device for switching a flow path of blood between a blood drawing tube connected to a blood drawing bag and an initially-drawn blood introducing tube connected to an initially-drawn blood removing bag (see, for example, JP 2008-149066 A).